Canopy cutting device

ABSTRACT

A canopy cutting device, for machining canopies and the like in constricted spaces, including a housing having a base plate, a bearing mounted on the housing, a support for retaining the axis of the bearing in a desired position, a ring gear carriage mounted on the bearing for rotation about the bearing, a cutting tool mounted on the carriage, a pinion gear mounted for rotation on the housing and engageable with the ring gear, a drive shaft connected to the pinion gear, and a feed device for advancing the cutting tool along the axis during rotation of the ring gear thereby permitting removal of a canopy or the like.

This is a division of application Ser. No. 884,245, filed Mar. 7, 1978,now U.S. Pat. No. 4,236,428.

BACKGROUND AND OBJECTS OF THE INVENTION

The present invention relates in general to portable lathes and moreparticularly to a canopy removing device designed for application onnuclear components to permit replacement or maintenance of variouscomponents.

In nuclear systems and the like, removable cylindrical components arejoined to other cylindrical components or are positioned in a bore whichresults in a need to seal the circumferential joints with protectivecanopies. These canopies span the joints to permit expansion andcontraction while preventing any contaminated material from passingthrough the joint. The canopies are normally truncated conical ringshaving an arcuate cross-section and being welded along its two edges tothe adjoining components. These canopies are normally formed of astainless steel as are the adjoining components. When it becomesnecessary to remove one of the components such as for maintenance,failure of a part or renewal of a fuel supply, the canopy must beremoved without contaminating the environment and without damagingeither of the two assembled components.

Previously, hand grinders have been utilized in removing canopies whichhas been extremely time-comsuming as shown by the fact that the removalof a 53/8th inch outside diameter canopy has required twelve hours ofhand grinding. Hand grinding has been exclusively employed for thispurpose in nuclear reactors in the past which has required the extensivetraining and employment of large numbers of operators due to the factthat each worker can remain at a work station for only a very short timeperiod to avoid over-exposure to radiation. Since the time required forthe entire grinding operation is substantial, a large number of handgrinding operators is required to complete the presently employedtedious and time-consuming process. In actuality, the radiation to whichthese workers are exposed results in their being able to work only a fewhours a month in performing tasks in this environment; moreover, thenuclear reactor environment requires the elimination of dust andlubrication, to avoid contamination which increases the exposure timefor the workers.

An additional problem arises from the fact that the canopies arefrequently located in very constricted spaces such as small diameterbores and areas closely adjacent other components resulting in difficultaccess to the canopy cutting and removal of the canopy.

Attempts have been made to provide a device for removing the canopieswithout damaging the components to which each canopy has been welded.These devices have been complex, bulky and heavy and have required theuse of skilled and expensive operators to remove even the canopies whichwere large and conveniently located. While this previous equipment hasreduced the time required for hand grinding removal of the canopies inmany instances, it has not been usable in restricted and confined spacesand has continued to require long periods of operation in radiationenvironments thereby requiring numerous operators to complete a giventask.

It is, therefore, a primary object of the present invention to provide anew and useful canopy cutting device.

An additional object of the present invention is to provide a novelcanopy cutting device which is extremely small compared to the itembeing removed thereby permitting its application to cutting operationsin extremely confined areas.

A further object of the present invention is to provide a novel canopycutting device which can perform efficient machining operations whenused by an inexperienced operator in very confined spaces.

A further object of the present invention is to provide a novel canopycutting device which drastically reduces the exposure of operators toradiation when the device is used to remove canopies in nuclearreactors.

Another object of the present invention is to provide a novel canopycutting device which is extremely simple in construction and requires aminimum of maintenance over a long useful life.

A further object of the present invention is to provide a novel canopycutting device which can be operated without any lubrication of thedevice or cutting tool while permitting the removal of stainless steel,inconel and other special alloys found in nuclear reactors and the likethereby eliminating a potential source of contamination and exposuretime to radiation which would result in attempting to clean up thecontamination.

A further object of the present invention is to provide a canopy cuttingdevice which is capable of facing or otherwise machining the componentto which the canopy is attached prior to installing another canopy.

A further object of the present invention is to provide a novel canopycutting device which does not have excessive chattering of the tool bitand operates smoothly without part breakage or stalling.

A still further object of the present invention is to provide a machinewhich is simple and safe to operate with a minimum of operator skill andwith all adjustments being convenient while the device is being operatedin either vertical or horizontal positions.

Other objects, advantages and capabilities of the present invention willbecome apparent from the following detailed description taken inconjunction with the accompanying drawings illustrating the preferredembodiment of the invention.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a top elevation view of a first embodiment of the presentinvention;

FIG. 2 is a side elevation view shown in the operating position prior toremoval of the weld and canopy shown in dotted lines;

FIG. 3 is a vertical sectional view, taken along line 3--3 in FIG. 1;

FIG. 4 is a horizontal sectional view taken along line 4--4 in FIG. 3;

FIG. 5 is an exploded perspective view of the canopy cutting device;

FIG. 6 is a top elevation view of an alternative embodiment of thepresent invention;

FIG. 7 is a side elevational view, taken along line 7--7 in FIG. 6;

FIG. 8 is a side elevational view of the radial feed mechanism takenalong lines 8--8 in FIG. 7;

FIG. 9 is a sectional side elevational view of a second alternativeembodiment;

FIG. 10 is a sectional view taken along line 10--10 in FIG. 9; and

FIG. 11 is a sectional view taken along line 11--11 in FIG. 9.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to the drawings wherein like reference characters designatecorresponding parts throughout the several figures, the canopy cuttingdevice of the present invention is indicated generally by the referencecharacter 30, and as shown in FIG. 5 includes a stub shaft assembly 32,a bearing assembly 34, a ring gear carriage assembly 36, a tool assembly38, a housing 40, a pinion drive gear assembly 42 and an axial feedassembly 44.

The canopy cutting device is supported on the stub shaft assembly 32, asbest shown in FIGS. 2, 3 and 5, and includes a circular base flangeplate 46 having a plurality of through bolt holes 48 positioned aroundthe outer edge thereof and registrable with threaded bores 50 of asupporting component 56, as illustrated in FIG. 3, to receive mountingbolts 52. The stub shaft assembly is secured in the desired position bybolts 52 with the axis of the stub shaft coincident with the axis of acanopy 54 which has been secured to adjacent components 56 and 58 bycircular or ringlike weld beads 60. Extending upwardly from the baseplate 46 is a stub shaft 62 having a free end 64 thereof threaded toengage and support the axial feed assembly 44. The stub shaft 62 hasdiametrically positioned longitudinal keyways 66 to receive keys 68which are retained in the keyways 66 by mounting bolts 70, as best shownin FIG. 3. An alternative embodiment 32' of the stub shaft flange isidentical to the embodiment 32 with the exception of eliminating thebolt holes 48 and adding a downwardly projecting outer lip 72 with setscrews 74 extending radially therethrough, as shown in FIG. 5, to permitclamping of the cup shaped base plate on a projecting portion of acomponent which is employed in some installations. It should beunderstood that the base plate can be of any of a wide variety ofconfigurations including means of attachment which is capable of rigidlypositioning the stub shaft 62 in the desired position.

The bearing assembly 34 is generally cylindrical in form having asmaller diameter upper portion 76 and a larger diameter lower portion 78with a through bore 80 sized to fit closely over the stub shaft 62 andhaving diametrically opposed keyways 82 which are sized to fit closelyover the keys 68 bolted to the stub shaft 62, as shown in FIG. 4. Theupper portion 76 and lower portion 78 may have circumferential grooves84 and 86, as best shown in FIGS. 3 and 5, to permit lubrication of thebearing in those applications where lubrication will not causecontamination. The bearing assembly is machined from bronze and becauseof its relatively large dimensions, has a long useful life. A coating orimpregnation with a material such as Teflon may be used on the outersurface of the bearing assembly 34 in those applications where extremelylow friction is desirable and lubrication is not permitted. Through boltholes 88 extending axially through the upper and lower portions 76 and78 of the bearing assembly to permit insertion of mounting bolts 90, asshown in FIGS. 3 and 5, to attach the bearing assembly to the housingassembly 40.

The ring gear and carriage assembly 36 is mounted for rotation onbearing assembly 34 as best shown in FIGS. 3 and 5 and is constructed ofhardened steel; the assembly is generally cylindrical in configurationwith a ring gear 92 being formed around the upper periphery thereof. Abore extends axially through the assembly 36 and includes a smalldiameter portion 84 and a larger diameter portion 86 to matingly engagethe upper and lower portions 76 and 78 of the bearing assembly 34 asshown in FIG. 3 to permit free rotation of the ring gear assembly aboutthe bearing assembly. A lower carrier portion 98 of the ring carrierassembly has a smaller outside diameter than the ring gear 92 and has atool receiving radial recess 100 as shown in FIGS. 3 and 5.

The tool assembly 38 includes a generally rectangular mounting toolblock 102 sized to closely fit in the recess 100 with bolt holes 104 inthe mounting block being registrable with threaded bores 105 in thecarrier portion 98 as shown in FIG. 3; mounting bolts 106 extend throughbolt holes 104 into threaded bores 105 to retain the tool assembly inthe recess 100. A cutting bit 108 is retained in an appropriate slot 110extending radially through the tool block 102 to project outwardly, asshown in FIG. 4, to engage the canopy 54 during the cutting operation.Tool bit 108 is retained in position by a set screw 112 shown in dottedlines in FIG. 2.

The housing assembly 40 includes a base plate 114 which is partiallycircular in shape and slightly larger than the diameter of the ring gearon one end with an opening 116 being provided to fit over, but nottouch, the stub shaft 62, as shown in FIG. 3. Threaded bores 118 (FIG.5) are positioned around opening 116 to be threadingly engaged bymounting bolts 90 which extend upwardly from the bearing assembly 34into into the base plate 114 as shown in FIG. 3.

The base plate 114 also includes an eccentric portion 120 having a driveshaft opening 122 therethrough opening into a larger diameter bearingreceiving bore 124 extending through the lower surface of the base plate114, as best shown in FIG. 3. A suitable guard 125 may be attached to aportion of the outer periphery of the base plate 114 and includes aninwardly directed lower lip 126 which extends beneath the ring gear 92as shown in FIG. 3 to prevent any accidental contact with the ring gear.The guard 125 is attached by appropriate screws or similar fasteners tothe base plate 114.

The ring gear 92 is driven by a drive pinion 128 in the pinion driveassembly 42 surrounding and keyed to a drive shaft 130 journaled inbearings 132 and 134. Bearing 132 is mounted in bearing receiving bore124 in base plate 114 and bearings 134 is mounted in a bearing supportplate 136 having a bearing receiving bore 138 and pinion clearance bore140 alignable with bores 122 and 124 in the base plate 114 to receivethe bearing 134 and the pinion gear 128 as shown in FIG. 3. The supportplate 136 may include extensions 142 which provide a guard for theportion of the ring gear 92 which is not protected by the shield 125 asbest shown in FIG. 2. The drive pinion support plate 136 may be attachedto the base plate 114 in the conventional manner by mounting bolts 144as shown in FIGS. 2 and 3. The drive shaft 130 has a nonround socket orrecess, such as a square cross-section socket, indicated at 130a, toreceive the drive shaft of a suitable driving tool, such as a pneumaticdrive motor, to drive the pinion 128 and ring gear 92. The ring gear 92upon rotation about the axis of the stub shaft 62, carries with it thecutting bit 108.

Axial feed is provided by the axial feed assembly 44 which includes anaxial feed nut 146 engageable with the threaded end 64 of the stub shaft62. The axial feed nut 146 has a radially projecting annular lip 148around the lower edge thereof to permit retention of the nut 146 in thedesired position relative to the base plate 114 by a retaining ring 150.An inwardly directed upper lip 151 having an inside diameter larger thanthe outside diameter of the nut 146 and a diameter smaller than theoutside diameter of the lip 148 to permit retention of the nut inposition in a shallow recess 152 formed around the opening 116 in thebase plate 114. The retaining ring 150 is bolted to the base plate 114by retaining bolts 154 such as to permit free rotation of the nut 146while preventing any axial movement relative to the base plate 114.Extending outwardly from the nut 146 are two pairs of diametricallyopposed pins positioned at right angles to permit manual rotation of thefeed nut when the operator presses against the pins 156 in the desireddirection to cause rotation of the nut on the stub shaft 62 therebymoving the cutting bit 108 either toward or away from the canopy asdesired.

Referring now to FIGS. 6, 7 and 8, there is disclosed a radial feedassembly 160 for use with the canopy cutter disclosed in FIGS. 1 through5. The radial feed assembly 160 includes a tool mounting block 102'which is bolted to the carrier portion 98 of the ring gear assembly 36in the same manner as tool mounting block 102 shown in FIGS. 2 and 3.The tool mounting block 102 supports a cutting tool holder 162 mountinga securely held cutting tool 164 and guided for reciprocative movementradially of the stub shaft axis toward and away from the stub shaft axisbetween guide members 166 and 167 fastened to the mounting block 102' asshown in FIG. 8. The cutting tool holder 162 is precisely advanced andretracted along its radial guide axis by a feed screw 168 threaded intoa threaded recess in the cutting tool holder 162 and having a shaftportion journaled in a mounting plate 170 fastened to the mounting plate102', as shown in FIG. 7. Outwardly of the mounting plate 170 is a wormgear 172 held on the shaft of the feed screw 168 and engaged with a worm174 journaled in a worm bracket 176 also fixed to the mounting plate102'. The worm 174 is fixed on a shaft or has an integral shaft portionextending therefrom on which is pinned or otherwise fixed a star wheel178 which is located beyond the periphery of the ring gear 92.

A feed pin 180, extending through a feed pin mounting bracket 182 whichis bolted to the base plate 114 of the housing assembly 40 by mountingbolts 184, has its lower end positionable in the circular path of themovement of the star wheel 178 as the star wheel is carried by the ringgear 92 to rotate the star wheel and the worm through a selected angulardistance. For example, the star wheel rotates one-sixth of a revolutioneach time the star wheel strikes the feed pin to advance the cuttingtool 164 inwardly through a selected small distance at least once duringeach revolution of the ring gear 92. In the embodiment shown in FIGS. 6and 7, the feed pin has a coil spring 184 surrounding the shank of thefeed pin between an enlarged head 186 and the bracket 182 with the feedpin being held in a drive position in which the enlarged head 186engages a feed pin retaining bracket 188. When feed pin 180 is in anelevated position, its lower end is higher than star wheel 178 so thatthe star wheel passes beneath and does not engage the pin 180 and thereis consequently no radial feed of the tool; however, feed pin 180 can bemoved downwardly to its drive position by manual engagement of head 186so as to position its lower end in the path of the star wheel so as toeffect rotation of the star wheel and resultant radial feed of the toolunder complete control of the operator.

Operation of the canopy cutting device is easily and quicklyaccomplished by a person of minimum skill and training by firstattaching an appropriate base plate assembly such as 32 or 32' andcentering the shaft to cause the tool bit 108 to rotate about thedesired axis for removal of the weld 60 and canopy 54. The operator thenaligns the keyways 82 in the bearing assembly 34 with the keys 68 on thestub shaft 62 and lowers the device until the feed nut 146 engages thethreaded end 64 of the stub shaft 62 at which time the operator manuallyrotates the feed nut 146 by applying torque to the pins 156 extendingtherefrom to lower the cutting tool to the desired beginning position.Drive power is then suitably applied to the drive shaft 130 such as by apneumatic drive motor which causes the drive pinion 128 to rotate anddrive ring gear 92 to cause the cutting assembly 38 to rotate about theaxis of the stub shaft. For a 53/8 inch outside diameter canopy, thering gear would be driven at approximately 50 revolutions per minute.The operator then rotates the feed nut 146 at an appropriate speedconsistent with the material being removed until the desired materialhas been removed at which time the drive shaft can be disconnected fromthe motor and the direction of rotation of the feed nut 146 reversed toremove the device from the stub shaft thereby completing the operation.

As can be seen, this extremely simple device, having very few parts, iseasily assembled and is capable of removing canopies in less than anhour which had previously required twelve hours of skilled hand grindingto remove.

Referring now to the embodiment shown in FIGS. 9, 10 and 11, there isillustrated a second alternative embodiment installed on a valve 190 and190' having a canopy 192 attached by welds 194 to the adjacent valvemembers. This embodiment is similar to those illustrated in FIGS. 1through 8 with the replacement of the keyway and axial feed nut of theother embodiments by a collet locking assembly 196 and an automaticaxial feed mechanism 198.

In this embodiment, the bearing assembly 34' has a truncated conicalbore portion 80' designed to receive an annular collet 200 having asubstantially triangular cross-section, as illustrated in FIG. 9, andhaving cuts 202 extending through a major portion of the axial length ofthe collet segment and spaced circumferentially thereof with alternatecuts opening through opposite ends of the collet to render the colletflexibly deformable. A collet nut 204 is threadably engageable with athreaded bore of the center opening of the bearing assembly and has asurface conforming to the adjacent surface of the collet and is forcedagainst the collet to cam them into tightly clamping relation with thevalve stem 190 to lock the canopy cutting device in the desiredposition. Radial feeding of the cutting tool 164' is accomplished in thesame manner as that described for the embodiment shown in FIG. 7 and thecorresponding parts are identified with primed numbers.

Reciprocative axial feed is accomplished by the automatic axial feedmechanism 198 mounted between an upper portion 102a and a lower portion102b forming the tool mounting block of this embodiment, as shown inFIG. 9. The lower portion 102b is guided in the axial direction by guidemembers 208 and 209 fastened to the upper portion 102a, as shown in FIG.10. The cutting tool holder 162' is precisely advanced and retractedalong the axial direction by a feed screw 210 threaded into a threadedrecess in the lower portion 102b and has a shaft portion journaled in abore 212 formed in the upper portion 102a as shown in FIG. 9, and has anintegral shaft portion extending therefrom on which is pinned orotherwise fixed a star wheel 214. A second feed pin 216 is mounted inthe feed pin support bracket 182' for axial movement between a driveposition in which its lower end is in the path of movement of star wheel214 and an elevated position in which its lower end is above the starwheel. Engagement of star wheel 214 with the lower end of the secondfeed pin 216 serves to rotate the star wheel through a selected angulardistance, for example, one-sixth of a revolution, each time the starwheel strikes the feed pin, to advance the cutting tool holder 162' andtool 164' axially through a selected small distance at least once duringeach revolution of the ring gear. In the embodiment herein illustrated,the feed pin has a coil spring 218 surrounding the shank of the feed pinbetween an enlarged head 220 and a lower surface of the support bracket182. The feed pin is held in position by a feed pin retaining bracket222.

From the foregoing detailed description, it will be evident that thereare a number of changes, adaptations and modifications of the presentinvention which come within the province of those skilled in the art.However, it is intended that all such variations not departing from thespirit of the invention be considered as within the scope thereof and aslimited solely by the appended claims.

I claim:
 1. A canopy cutting device for machining canopies and the likein constricted spaces, said device comprising a housing including a baseplate, a bearing mounted on said housing and having an axis, means forretaining the axis of said bearing in a desired position, a ring gearmounted on said bearing for rotation about said bearing, a cutting toolmounted on and externally of said ring gear, a pinion gear mounted forrotation on said housing and engageable with teeth extending about theouter periphery of said ring gear, means for driving said pinion gearand means for advancing said cutting tool along a line parallel to saidaxis, means for advancing said cutting tool along a line perpendicularto said axis during rotation of the ring gear thereby permitting removalof a canopy or the like, wherein said means for advancing said cuttingtool includes a cutting tool holder slidably mounted on the ring gearfor axial and radial reciprocative movement and supporting the cuttingtool, feed screw means for moving said cutting tool holder, indexingwheel means coupled to the feed screw means and extending outwardlybeyond the perimeter of the ring gear and carried in a circular pathabout the axis during rotation of the ring gear and feed pin meanspositionable in said circular path of movement of the indexing wheelmeans to intercept and rotate the indexing wheel means through aselected increment for driving the feed screw means to advance thecutting tool holder through one step.
 2. The canopy cutting device ofclaim 1 wherein said means for retaining the axis of said bearing in adesired position comprises a collet and means for compressing saidcollet around a desired cylindrical component.
 3. The canopy cuttingdevice of claim 1 wherein two feed pins are respectively provided forengaging two respective star wheels for respectively effecting radialand axial feeding of said cutting tool holder.
 4. The canopy cuttingdevice of claim 3 additionally including spring means for biasing saidfeed pins into a position in which the feed pins are not in the path ofmovement of the two respective indexing wheels each of which is a starwheel.
 5. The canopy cutting device of claim 4 wherein said means forretaining the axis of said bearing in a desired position comprises acollet and means for compressing said collet around a desiredcylindrical component.
 6. The canopy cutting device of claim 2 whereintwo feed pins are respectively provided for engaging indexing wheelscomprising two respective star wheels for respectively effecting radialand axial feeding of said cutting tool holder.
 7. The canopy cuttingdevice of claim 1 wherein said feed pin means is mounted for axialmovement between a first position out of the path of movement of theindexing wheel and a second position in the path of movement of theindexing wheel.
 8. The canopy cutting device of claim 7 additionallyincluding spring means for urging said feed pin means toward said firstposition.
 9. The canopy cutting device of claim 8 wherein said means forretaining the axis of said bearing in a desired position comprises acollet and means for compressing said collet around a desiredcylindrical component.